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Edmund Optics (Edmund) filed petitions requesting inter partes review (IPR) of two related patents belonging to Semrock. Both requests were instituted (hereinafter the “First Case” and the “Second Case”). Because the two cases involved related patents, Edmund used the same technical expert for both proceedings. To support its claim construction in the First Case, Semrock introduced the Edmund’s expert testimony from the Second Case. In particular, Semrock submitted deposition and declaration testimony from Edmund’s expert in the Second Case with its papers in the First Case. Edmund objected to Semrock’s maneuver and filed a motion to exclude.

In its motion, Edmund argued that testimony from its expert in the related proceeding was inadmissible because the testimony was outside the scope of its expert’s testimony in the First Case, because it was hearsay and because the testimony was not relevant to the claims sought to be construed. With respect to deposition testimony, Edmund further averred that the parties agreed to treat the depositions in the two cases as separate—assigning separate days for each proceeding.

Going a step further, Edmund argued that “admissions” by its expert in the instant proceeding (i.e., First Case) were also inadmissible. Edmund alleged that its expert did not understand the legal significance of the term “disclose” when cross-examined about whether the prior art failed to disclose elements of the claimed invention.

The Board disagreed that testimony from another proceeding was inadmissible and declined to exclude it. The Board reasoned that the expert’s testimony from the related proceeding was at least relevant to claim construction and was therefore admissible. At the same time, because the testimony was offered as extrinsic evidence on the issue of claim construction, the Board assigned it little weight. The Board also rebuffed Edmund’s attempt to exclude cross-examination testimony of its expert in the case at issue. The Board pointed-out that Edmund’s expert had even used the term “disclose,” or variations of it, more than 50 times in his own declaration when discussing the prior art. Accordingly, there was no evidence tending to show that Edmund’s expert had a materially different understanding of the word “disclose” in cross-examination than in his declaration.

Practice Note: This case should serve as a cautionary tale to patent practitioners who are considering using the same expert in multiple proceedings. In a footnote of the Final Decision, the Board explained that it was disinclined to adopt a “blanket rule” that cross-examination testimony obtained in one case can never be used in another. The Board posited that testimony in another proceeding may be appropriate, for example, to impeach a witness with a prior inconsistent statement.

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